Data transmitting apparatus, data receiving apparatus, data transmitting method, and data receiving method

ABSTRACT

The present invention provides a data transmitting apparatus in which a device information obtaining unit obtains device information of a device connected to the data transmitting apparatus; a verification unit verifies validity of a data receiving apparatus, based on the device information obtained by the device information obtaining unit; and a control unit performs control as to whether to obtain the device information through a wireless communication unit or obtain the device information through a wire communication unit, and as to whether to transmit image information encrypted by a first encryption unit from the wireless communication unit or transmit image information encrypted by a second encryption unit from the wire communication unit when the verification unit verifies that the data receiving apparatus is authorized.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese Patent ApplicationJP 2008-181728 filed in the Japanese Patent Office on Jul. 11, 2008, theentire content of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a data transmitting apparatus, a datareceiving apparatus, a data transmitting method, and a data receivingmethod. More particularly, the present invention relates to a datatransmitting apparatus, a data receiving apparatus, a data transmittingmethod, and a data receiving method that verify the validity of a devicein wireless communication.

2. Description of the Related Art

In related art, for the purpose of protecting the copyright of musiccontent, video content, etc., various protocols, e.g., HDMI(High-Definition Multimedia Interface), are proposed. For a contentprotection scheme, for example, HDCP (High-bandwidth Digital ContentProtection system) is used. The HDCP standard defines a key sharingscheme for device authentication or authentication between thetransmitting side and the receiving side, an encryption scheme forcontent to be transmitted, etc.

In authentication based on the HDCP standard, etc., a device key forindividually authenticating a communication partner's apparatus bypublic key encryption is used. When authentication between atransmitting apparatus and a receiving apparatus succeeds, thetransmitting apparatus encrypts a video signal using a device key andtransmits the encrypted video signal and the receiving apparatusdecrypts the received video signal using a device key.

Also, in the HDCP standard, the above-described authentication processis performed and a so-called revocation process for determining whetherthe receiving apparatus is an unauthorized device is performed. Onlyafter the receiving apparatus is determined by the revocation processnot to be an unauthorized device, encryption transmission is enabled.

In the case of a device that wirelessly transmits an image signal, also,when a secure connection is established using HDMI, etc., between asource device, such as a recording and reproducing apparatus, and awireless device (data transmitting apparatus) and between a wirelessdevice (data receiving apparatus) and a sink device such as a display,the devices can mutually determine whether they are authorized devices,by using security information stored in each device. Consequently,allowance for signal transmission between differing transmitting andreceiving devices is enabled.

-   [Patent Document 1] Japanese Patent Application Laid-Open No.    2003-37591-   [Patent Document 2] Japanese Patent Application Laid-Open No.    2006-128963

SUMMARY OF THE INVENTION

However, when, for example, a data receiving apparatus is built in adisplay, etc., and thus the security information based on HDCP, etc., isnot stored on the receiving side, content may not be protected againstunauthorized copying unless the data receiving apparatus is always usedwith a specific data transmitting apparatus as a pair. Accordingly,there is an issue of poor usability.

In wireless communication, image data is transmitted in a manner suchthat image data compression according to an image signal, etc., areperformed by a method using a DCT/Wavelet transform, etc., to reducetransfer rate. Hence, when content data is encrypted based on HDCP,after the content data is decrypted the content data needs to beencrypted again to transmit image data by wireless communication.Accordingly, there is an issue that the process becomes complex.

The present invention has been made in view of the above-describedissues and it is desirable to provide novel and improved datatransmitting apparatus, data receiving apparatus, data transmittingmethod, and data receiving method that are capable of performingencryption by wireless communication and verifying the validity of adevice.

According to an embodiment of the present invention, there is provided adata transmitting apparatus including: a first encryption unit thatencrypts image information of input content with a first encryptionscheme; a wireless communication unit that transmits, by wirelesscommunication, the image information encrypted by the first encryptionunit; a second encryption unit that encrypts image information of inputcontent with a second encryption scheme; a wire communication unit thattransmits, by wire communication, the image information encrypted by thesecond encryption unit; a device information obtaining unit that obtainsdevice information of a device connected to the data transmittingapparatus; a verification unit that verifies validity of a datareceiving apparatus, based on the device information obtained by thedevice information obtaining unit; and a control unit that performscontrol as to whether to obtain the device information through thewireless communication unit or obtain the device information through thewire communication unit, and as to whether to transmit the imageinformation encrypted by the first encryption unit from the wirelesscommunication unit or transmit the image information encrypted by thesecond encryption unit from the wire communication unit when theverification unit verifies that the data receiving apparatus isauthorized.

According to the configuration, when the data transmitting apparatus isconnected to a data receiving apparatus by wireless communication,device information of the data receiving apparatus is obtained throughthe wireless communication unit. When the data receiving apparatus isverified to be authorized, image information encrypted by the firstencryption unit is transmitted from the wireless communication unit.When the data transmitting apparatus is connected to a data receivingapparatus by wire communication, device information of the datareceiving apparatus is obtained through the wire communication unit.When the data receiving apparatus is verified to be authorized, imageinformation encrypted by the second encryption unit is transmitted fromthe wire communication unit.

Consequently, when image information of content is transmitted inwireless communication, the image information can be encrypted with thefirst encryption scheme which is normally used for wirelesscommunication. Also, even in wireless communication, the validity ofdevice information can be verified. Even when wireless communication isperformed, the validity of a data receiving apparatus can beauthenticated using wire-input security information. Thus, even whenHDCP security information is not stored on the receiving side,transmission and reception of content data can be performed with anydevice other than a specific transmitting apparatus, with the copyrightof the content data being protected.

When the data transmitting apparatus is connected to the data receivingapparatus by wireless communication, the control unit may control theverification unit to verify the validity of the data receiving apparatusand control the first encryption unit to encrypt the image information.The device information obtaining unit obtains information onunauthorized devices from an external apparatus, and when the deviceinformation of the data receiving apparatus is not included in theinformation on unauthorized devices obtained by the device informationobtaining unit, the verification unit may determine that the datareceiving apparatus is an authorized device.

The first encryption unit may compress the image information of inputcontent according to the image information and thereafter encrypt thecompressed image information with the first encryption scheme. Thesecond encryption unit may encrypt the image information of inputcontent with the second encryption scheme and thereafter TMDS-convertthe encrypted image information.

The wire communication unit may transmit the image information ofcontent through a TMDS circuit. The verification unit may verify thedata receiving apparatus, based on an HDCP standard.

According to another embodiment of the present invention, there isprovided a data receiving apparatus including: a wireless communicationunit that receives image information of content by wirelesscommunication from a data transmitting apparatus connected to the datareceiving apparatus; a first decryption unit that decrypts the receivedimage information of content with a first decryption scheme; a wirecommunication unit that receives image information of content from thedata transmitting apparatus by wire communication; a second decryptionunit that decrypts the received image information of content with asecond decryption scheme; a device information obtaining unit thatobtains device information of a device connected to the data receivingapparatus; a verification unit that verifies validity of the device,based on the device information obtained by the device informationobtaining unit; and a control unit that performs control as to whetherto obtain the device information through the wireless communication unitor obtain the device information through the wire communication unit,and as to whether to receive the image information by the wirelesscommunication unit and decrypt the image information by the firstdecryption unit or receive the image information by the wirecommunication unit and decrypt the image information by the seconddecryption unit when the verification unit verifies that the device isauthorized.

According to the configuration, when the data receiving apparatus isconnected to a data transmitting apparatus by wireless communication,image information of content is received from the data transmittingapparatus through the wireless communication unit and device informationof a device connected to the data receiving apparatus is obtained bywireless communication. When the connected device is verified to beauthorized, image information encrypted by the first encryption unit istransmitted from the wireless communication unit. When image informationof content is received from the data transmitting apparatus by wirecommunication, device information of a device connected to the datareceiving apparatus is obtained through the wire communication unit.When the connected device is verified to be authorized, imageinformation encrypted by the second encryption unit is transmitted fromthe wire communication unit.

Consequently, when image information of content is transmitted andreceived in wireless communication, image information of content isreceived by wireless communication and the received image informationcan be encrypted with the first encryption scheme which is normally usedfor wireless communication. Also, even in wireless communication, thevalidity of device information can be verified. Even when wirelesscommunication is performed, the validity of a connected device can beauthenticated using security information provided for a wire input.Thus, even when HDCP security information for wireless is not stored onthe receiving side, transmission and reception of content data can beperformed with any device other than a specific transmitting apparatus,with the copyright of the content data being protected. For example,when image information of content is transmitted from the data receivingapparatus by wireless communication to a sink device such as a display,the validity of the sink device can be verified using wire-inputsecurity information stored in the display, etc.

When the data receiving apparatus is connected to the device by wirelesscommunication, the control unit may control the verification unit toverify the validity of the device and control the first decryption unitto decrypt the image information. The device information obtaining unitmay obtain information on unauthorized devices from an externalapparatus, and when the device information of the device is not includedin the information on unauthorized devices obtained by the deviceinformation obtaining unit, the verification unit may determine that thedevice is an authorized device.

The first decryption unit may compress the image information of contentaccording to the image information and thereafter decrypt the compressedimage information with the first decryption scheme. The seconddecryption unit may decrypt the image information of content with thesecond decryption scheme and thereafter TMDS-convert the decrypted imageinformation.

The wire communication unit may transmit the image information ofcontent through a TMDS circuit. The verification unit may verify thedata receiving apparatus, based on an HDCP standard.

According to another embodiment of the present invention, there isprovided a data receiving apparatus including: a wireless communicationunit that receives image information of content by wirelesscommunication from a data transmitting apparatus connected to the datareceiving apparatus; a first decryption unit that decrypts the receivedimage information of content with a first decryption scheme; a wirecommunication unit that receives image information of content from thedata transmitting apparatus by wire communication; a second decryptionunit that decrypts the received image information of content with asecond decryption scheme; a device information transmitting unit thattransmits device information of the data receiving apparatus; averification result obtaining unit that obtains a verification result ofvalidity of the data receiving apparatus which is verified by the datatransmitting apparatus, based on the device information transmitted fromthe device information transmitting unit; a control unit that performscontrol as to whether to transmit the device information through thewireless communication unit or transmit the device information throughthe wire communication unit, and as to whether to receive the imageinformation by the wireless communication unit and decrypt the imageinformation by the first decryption unit or receive the imageinformation by the wire communication unit and decrypt the imageinformation by the second decryption unit when the verification resultobtaining unit obtains a verification result that the data receivingapparatus is authorized; and a display screen generating unit thatgenerates a display screen containing the image information decrypted bythe first decryption unit or the second decryption unit.

According to the configuration, when the data receiving apparatus isconnected to a data transmitting apparatus by wireless communication,device information of the data receiving apparatus is transmitted bywireless communication. When the validity of the data receivingapparatus is confirmed, image information of content is received fromthe data transmitting apparatus through the wireless communication unit.Then, the image information of content is decrypted with the firstdecryption scheme and a display screen containing the decrypted imageinformation is generated. When the data receiving apparatus is connectedto a data transmitting apparatus by wire communication, deviceinformation of the data receiving apparatus is transmitted by wirecommunication. When the validity of the data receiving apparatus isconfirmed, image information of content is received from the datatransmitting apparatus through the wire communication unit. Then, theimage information of content is decrypted with the second decryptionscheme and a display screen containing the decrypted image informationis generated.

Consequently, when image information of content is transmitted andreceived in wireless communication, image information of content isreceived by wireless communication and the received image informationcan be decrypted with the first decryption scheme which is normally usedfor wireless communication. Even when wireless communication isperformed, the validity of a connected device can be authenticated usingsecurity information for a wire input. Thus, even when HDCP securityinformation for wireless is not stored on the receiving side,transmission and reception of content data can be performed with anydevice other than a specific transmitting apparatus, with the copyrightof the content data being protected. For example, when a data receivingapparatus and a display apparatus are configured into one unit, thevalidity of the data receiving apparatus can be verified usingwire-input security information stored in the display apparatus, etc.

The display screen generating unit is included in a display apparatuswhich is built in the data receiving apparatus, the device informationtransmitting unit transmits device information of the display apparatus,and the verification result obtaining unit may obtain a verificationresult of validity of the data receiving apparatus which is verified bythe data transmitting apparatus, based on the device information of thedisplay apparatus.

The first decryption scheme may be used when image information ofcontent is transmitted by wireless communication. The second decryptionscheme may perform HDCP standard-based decryption on image informationof content transmitted by wire communication.

The wire communication unit may receive the image information of contentthrough a TMDS circuit. The verification result obtaining unit mayobtain a verification result of the validity of the data receivingapparatus which is verified based on an HDCP standard.

According to another embodiment of the present invention, there isprovided a data transmitting method including the steps of: encryptingimage information of input content with a first encryption scheme;encrypting image information of input content with a second encryptionscheme; determining whether to obtain device information of a deviceconnected through a wireless communication unit that receives imageinformation of content by wireless communication or obtain the deviceinformation through a wire communication unit that receives imageinformation of content by wire communication, and obtaining the deviceinformation of the device; verifying validity of a data receivingapparatus, based on the obtained device information; and when the datareceiving apparatus is verified to be authorized, performing control asto whether to transmit the image information encrypted with the firstencryption scheme from the wireless communication unit or transmit theimage information encrypted with the second encryption scheme from thewire communication unit.

According to another embodiment of the present invention, there isprovided a data receiving method including the steps of: decryptingimage information of content received from a data transmittingapparatus, with a first decryption scheme; decrypting image informationof content received from the data transmitting apparatus, with a seconddecryption scheme; performing control as to whether to obtain deviceinformation of a device connected through a wireless communication unitthat receives image information of content by wireless communication orobtain the device information through a wire communication unit thatreceives image information of content by wire communication; obtainingthe device information of the device; verifying validity of the device,based on the obtained device information; and when the device isverified to be authorized, performing control as to whether to receivethe image information by the wireless communication unit and decrypt theimage information with the first decryption scheme or receive the imageinformation by the wire communication unit and decrypt the imageinformation with the second decryption scheme.

According to another embodiment of the present invention, there isprovided a data receiving method including the steps of: decryptingimage information of content received from a data transmittingapparatus, with a first decryption scheme; decrypting image informationof content received from the data transmitting apparatus, with a seconddecryption scheme; performing control as to whether to transmit deviceinformation of a data receiving apparatus through a wirelesscommunication unit that receives image information of content bywireless communication or transmit the device information through a wirecommunication unit that receives image information of content by wirecommunication; transmitting the device information; obtaining averification result of validity of the data receiving apparatus which isverified by the data transmitting apparatus, based on the transmitteddevice information; when a verification result that the data receivingapparatus is authorized is obtained, performing control as to whether toreceive the image information by the wireless communication unit anddecrypt the image information with the first decryption scheme orreceive the image information by the wire communication unit and decryptthe image information with the second decryption scheme; and generatinga display screen containing the image information decrypted with thefirst decryption scheme or the second decryption scheme.

According to the embodiments of the present invention described above,encryption by wireless communication can be performed and the validityof a device can be verified.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 a and 1 b are illustrative diagrams describing a summary of datatransmitting and receiving systems according to embodiments of thepresent invention;

FIG. 2 is a block diagram showing the functional configurations of adata transmitting apparatus and a sink device according to a firstembodiment of the present invention;

FIG. 3 is an illustrative diagram describing an authentication processand a revocation process based on an HDCP standard, according to thefirst embodiment;

FIG. 4 is an illustrative diagram describing the case in which contentdata is transmitted and received by wireless communication, according tothe first embodiment;

FIG. 5 is a flowchart showing data transmitting and receiving methodsaccording to the first embodiment;

FIG. 6 is a timing chart showing a connection process by wirelesscommunication, according to the first embodiment;

FIG. 7 is a timing chart showing an HDCP authentication processaccording to the first embodiment;

FIG. 8 is a timing chart showing an image information transmissionprocess according to the first embodiment; and

FIG. 9 is a block diagram showing the functional configurations of adata transmitting apparatus and a data receiving apparatus according toa second embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the appended drawings. Note that,in this specification and the appended drawings, structural elementsthat have substantially the same function and structure are denoted withthe same reference numerals, and repeated explanation of thesestructural elements is omitted.

First, a summary of data transmitting and receiving systems according toembodiments of the present invention will be described. FIGS. 1 a and 1b are illustrative diagrams showing exemplary configurations of datatransmitting and receiving systems 1 and 2 according to the embodimentsof the present invention. As shown in FIG. 1 a, the data transmittingand receiving system 1 includes a source device 400 such as a recordingand reproducing apparatus, a data transmitting apparatus 100, a datareceiving apparatus 200, and a sink device 300 such as a display. Asshown in FIG. 1 b, the data transmitting and receiving system 2 includesa source device 400 such as a recording and reproducing apparatus, adata receiving apparatus 200, and a sink device 500 such as a display(which also performs data reception).

The source device 400 is an apparatus that records and reproducescontent of a television program, a movie, etc. The source device 400 hasa function of outputting content data from an output apparatus of thesource device 400, using a content protection scheme based on HDCP(High-bandwidth Digital Content Protection system), etc. Here, thesource device 400 and the data transmitting apparatus 100 comply with aninterface standard, e.g., HDMI (High-Definition Multimedia Interface),and transmit content data using a transmission scheme such as TMDS(Transition Minimized Differential Signaling).

In the data transmitting and receiving system 1, the data transmittingapparatus 100 is connected to the data receiving apparatus 200 bywireless communication and encrypted content data is transmitted fromthe data transmitting apparatus 100 to the data receiving apparatus 200.Then, the content data received by the data receiving apparatus 200 isdisplayed on the sink device 300, such as a display of a television set,connected by wire to the data receiving apparatus 200.

In the data transmitting and receiving system 2, also, likewise, contentdata is output from the source device 400 through the data receivingapparatus 200. The data receiving apparatus 200 and the sink device 500which also performs data reception are connected to each other bywireless communication. Encrypted content data is transmitted from thedata receiving apparatus 200 and is received by the sink device 500 andis then displayed on a display, etc., in the sink device 500.

As described above, the source device 400 and the data receivingapparatus 200 perform transmission of content data, using a contentprotection scheme based on HDCP, etc. The HDCP standard defines a keysharing scheme for device authentication or authentication between thetransmitting side and the receiving side, an encryption scheme forcontent to be transmitted, etc. In authentication based on the HDCPstandard, a device key for individually authenticating a communicationpartner's apparatus by public key encryption is used. Whenauthentication between a transmitting apparatus and a receivingapparatus succeeds, the transmitting apparatus encrypts a video signalusing a device key and transmits the encrypted video signal and thereceiving apparatus decrypts the received video signal using a devicekey.

Furthermore, in the HDCP standard, the above-described authenticationprocess is performed and a so-called revocation process for determiningwhether the receiving apparatus is an unauthorized device is performed.Only after the receiving apparatus is determined by the revocationprocess not to be an unauthorized device, encryption transmission isenabled.

In FIG. 1 a, when a secure connection is established using HDMI, etc.,not only between the source device 400 and the data transmittingapparatus 100 but also between the data receiving apparatus 200 and thesink device 300, the devices can mutually determine whether they areauthorized devices, by using security information stored in each device.Consequently, allowance for signal transmission between differingtransmitting and receiving devices is enabled.

However, when, as shown in FIG. 1 b, a data receiving apparatus is builtin a display, etc., and thus security information based on HDCP, etc.,stored in the sink device 500 may not be used, unauthorized copying maynot be prevented unless the sink device 500 is used with a specific datatransmitting apparatus as a pair, resulting in poor usability. Inwireless communication, image data is transmitted in a manner such thatimage data compression according to an image signal, etc., are performedby a DCT/Wavelet transform, etc., to reduce transfer rate. Hence, whencontent data is encrypted based on HDCP, after the content data isdecrypted the content data needs to be encrypted again to transmit imagedata by wireless communication.

Normally, the sink device 500 such as a display is provided with a wireinput in addition to a wireless input. Thus, in the present embodiment,by using wire-input security information, the data receiving apparatus200 and the sink device 500 are authenticated to be authorized devices.By using wire-input security information, an HDCP revocation process canbe performed even in wireless communication. Consequently, even inwireless communication, the validity of a device can be verified basedon HDCP, and thus, even when HDCP security information is not stored onthe receiving side, transmission and reception of content data can beperformed with any device other than a specific transmitting apparatus,with the copyright of the content data being protected.

This is all about a summary of the data transmitting and receivingsystems 1 and 2. First, the data transmitting and receiving system 2will be described. First, the functional configuration of the datatransmitting and receiving system 2 will be described with reference toFIG. 2.

FIG. 2 is a block diagram showing the functional configurations of thedata transmitting apparatus 100 and a data receiving portion of the sinkdevice 500 which also performs data reception. In the presentembodiment, the data transmitting apparatus 100 and the sink device 500can be connected to each other by wireless communication or wirecommunication. Image information of content is input to the datatransmitting apparatus 100. The image information is input to the sinkdevice 500.

As shown in FIG. 2, the data transmitting apparatus 100 includes aswitching unit 102, a control unit 104, a first encryption unit 106, asecond encryption unit 108, an HDCP authentication processing unit 110,a device information obtaining unit 112, a verification unit 114, astorage unit 116, a wireless communication unit 118, a wirecommunication unit 120, and a switching unit 122. The sink device 500includes a switching unit 502, a control unit 504, a first encryptionunit 506, a second encryption unit 508, an HDCP authenticationprocessing unit 510, a device information obtaining unit 512, averification unit 514, a storage unit 516, a wireless communication unit518, a wire communication unit 520, and a switching unit 522.

Before describing in detail the functional configurations of the datatransmitting apparatus 100 and the sink device 500, an authenticationprocess and a revocation process based on the HDCP standard will bedescribed with reference to FIG. 3. As shown in FIG. 3, a TX 10 which isan apparatus that transmits content data and an RX 20 which is anapparatus that receives the content data are HDMI-connected to eachother. In a normal HDMI connection, there are a TMDS signal path used totransmit an image signal and a DDC signal path used to transmit HDCPauthentication information, etc.

The HDMI-connected TX 10 and RX 20 perform an authentication processbased on the HDCP standard, etc. Specifically, the HDCP standardimplements protection of the copyright of content data by performing thefollowing processes (1) to (3):

-   -   (1) Authentication and sharing of a shared key between the TX 10        and the RX 20    -   (2) Encryption/decryption of content data with the shared key    -   (3) Revocation process using a KSV

In (1), the TX 10 and the RX 20 mutually perform authentication using asecret key provided in advance to the TX 10 and the RX 20, and a sharedkey required to encrypt data is shared between the TX10 and the RX 20.The shared key is shared only between those devices that are directlyconnected to each other in the course of an authentication process basedon the HDCP standard.

In (2), the TX 10 encrypts data using the shared key shared in theprocess (1) and transmits the encrypted data based on TMDS 11, and theRX 20 decrypts the data using the shared key.

In (3), a so-called revocation process is performed for determiningwhether the RX 20 is an unauthorized device, by using a KSV (KeySelection Vector) which is uniquely set according to a secret key ofeach device in HDCP. Specifically, the RX 20 transmits its KSV to the TX10 and the TX 10 obtains a KSV list of unauthorized devices from asource device, etc. The TX 10 then verifies whether the KSV of the RX 20is included in the obtained KSV list. If the KSV of the RX 20 isincluded in the KSV list, then the RX 20 is considered to be a devicethat has performed an unauthorized operation and thus the content datais not transmitted to the RX 20.

Accordingly, transmission of content data based on the TMDS 11 from theTX 10 to the RX 20 shown in FIG. 3 is performed after an authenticationprocess including a revocation process based on HDCP succeeds.Consequently, content data can be prevented from being transmitted to anunauthorized device, enabling to protect the copyright of the contentdata. This is all about an authentication process and a revocationprocess based on the HDCP standard.

Next, the case in which content data is transmitted and received bywireless communication will be described with reference to FIG. 4. Whencontent data is transmitted and received by wireless communication,transmission and reception of content data are performed through awireless TX 15 that transmits data by wireless communication and awireless RX 25 that receives the data by wireless communication.Normally, modulation at an encryption strength equal to that used for aTMDS signal is performed between the wireless TX 15 and the wireless RX25. When image information, etc., are transmitted by wirelesscommunication, image information, etc., are transmitted in a manner suchthat image data compression according to an image signal, etc., areperformed by a method using a DCT/Wavelet transform, etc., to reducetransfer rate. Hence, when content data is encrypted based on HDCP,after the content data is decrypted the content data needs to beencrypted again to transmit image data by wireless communication.Accordingly, the process becomes complex.

Meanwhile, in the HDCP standard, when an encryption strength equal tothat for the TMDS signal path is ensured, transmission through the TMDSsignal path does not need to be performed. Hence, when content data istransmitted and received by wireless communication, by performing datatransmission and reception by the wireless TX 15 and the wireless RX 25without performing data transmission and reception based on TMDS 11 andTMDS 21, the above-described complex encryption/decryption processes donot need to be performed.

However, even if an encryption strength equal to that for the TMDSsignal path is ensured by wireless communication, unless theabove-described HDCP revocation process is performed, content may not beprotected. When a revocation process is not performed, even when thewireless RX 25 is an unauthorized device which is not allowed to receivecontent data, content data is transmitted to the wireless RX 25. In viewof this, as for whether the device is unauthorized, by using an HDCPrevocation process, content can be protected even in wirelesscommunication.

For example, when the wireless RX 25 is built in a display, etc., andthus security information based on HDCP, etc., is not stored in thewireless RX 25, the revocation process may not be performed andaccordingly content may not be protected against unauthorized copyingunless the wireless RX 25 is always used with the specific wireless TX15 as a pair. However, by performing a revocation process using securityinformation stored in the display, etc., encryption by wirelesscommunication can be used and a revocation process can be performed.Consequently, even in wireless communication, mutual authenticationbetween devices can be performed and a transmitting device and areceiving device can be arbitrarily combined. This is all about the casein which content data is transmitted and received by wirelesscommunication.

Returning to FIG. 2, the first encryption unit 106 has a function ofencrypting image information of input content with a first encryptionscheme. The first encryption scheme is used when content data (imageinformation) is transmitted by wireless communication, and is ensuredwith an encryption strength equal to that for the above-described TMDS.Alternatively, the first encryption unit 106 may compress imageinformation of input content according to the image information andthereafter encrypt the compressed image information with the firstencryption scheme. For compression of image information, a method using,for example, a DCT/Wavelet transform (time-frequency componenttransform) can be used.

The second encryption unit 108 has a function of encrypting imageinformation of input content with a second encryption scheme. The secondencryption scheme performs encryption based on the HDCP standard,specifically, encryption using a shared key which is shared only betweenthose devices that are directly connected to each other in the course ofan authentication process. Also, the second encryption unit 108 mayTMDS-convert the encrypted image information of content. Furthermore,the second encryption unit 108 may perform a process in synchronizationwith an authentication process by the HDCP authentication processingunit 110. Specifically, after authentication by the HDCP authenticationprocessing unit 110 succeeds, encryption with the second encryptionscheme is performed.

The wireless communication unit 118 is a communication interface such asa wireless LAN (Local Area Network) compatible communication apparatusor a wireless USB compatible communication apparatus. The wirelesscommunication unit 118 has a function of transmitting, by wirelesscommunication, image information encrypted by the first encryption unit106.

The wire communication unit 120 is a communication interface such as awire communication apparatus which performs communication by wire. Anexample of the wire communication unit 120 includes a wire connectionunit that complies with the HDMI standard. The wire communication unit120 has a function of transmitting, by wire communication, imageinformation encrypted by the second encryption unit 108.

The HDCP authentication processing unit 110 performs the above-describeddevice authentication based on the HDCP standard. The HDCPauthentication processing unit 110 includes the device informationobtaining unit 112 and the verification unit 114. The device informationobtaining unit 112 has a function of obtaining device information of adevice connected to the data transmitting apparatus 100. The deviceinformation is, as described above, a KSV which is uniquely setaccording to a secret key of each device. KSVs are obtained from thesink device 500 to which image information is to be transmitted and adevice connected further theredown.

The source device 400 has a function of verifying the validity of thesink device 500 and a device connected further theredown, based ondevice information obtained by the data transmitting apparatus 100.Specifically, the source device 400 verifies the validity of the sinkdevice 500, etc., based on whether the KSVs of the sink device 500,etc., are included in the above-described KSV list of unauthorizeddevices. Based on results of the verification, the source device 400determines whether to perform output.

The control unit 104 has a function of performing control as to whetherto transmit and receive data using the wireless communication unit 118or transmit and receive data using the wire communication unit 120, bycontrolling switching of the switching unit 102 or the switching unit122. Specifically, when wireless communication is performed with thesink device 500 by switching the switching unit 122, device informationto be obtained by the device information obtaining unit 112 is obtainedthrough the wireless communication unit 118. When wire communication isperformed with the sink device 500, the switching unit 122 is switchedto obtain the device information through the wire communication unit120.

When the verification unit 114 verifies that the sink device 500 is anauthorized device, the switching unit 122 is switched to transmitencrypted image information to the sink device 500 through the wirelesscommunication unit 118 or the wire communication unit 120. When wirelesscommunication is performed with the sink device 500 by controlling theswitching of the switching unit 102, image information may be encryptedby the first encryption unit 106. When wire communication is performedwith the sink device 500, image information may be encrypted by thesecond encryption unit 108.

Examples of the storage unit 116 include nonvolatile memories such as anEEPROM (Electrically Erasable Programmable Read-Only Memory) and anEPROM (Erasable Programmable Read-Only Memory). The storage unit 116 canstore a KSV of the sink device 500, a KSV list of unauthorized devices,etc., obtained by the HDCP authentication processing unit 110.

This is all about the functional configuration of the data transmittingapparatus 100. Next, the functional configuration of the sink device 500will be described. The wireless communication unit 518 is acommunication interface such as a wireless LAN compatible communicationapparatus or a wireless USB compatible communication apparatus. Thewireless communication unit 518 has a function of receiving imageinformation of content transmitted from the data transmitting apparatus100 by wireless communication.

The wire communication unit 520 is a communication interface such as awire communication apparatus which performs communication by wire. Anexample of the wire communication unit 520 includes a wire connectionunit that complies with the HDMI standard. The wire communication unit520 has a function of receiving image information of content transmittedfrom the data transmitting apparatus 100 by wire communication.

The first encryption unit 506 has a function of encrypting imageinformation of content received by the wireless communication unit 518,with a first encryption scheme. The first encryption scheme is used whencontent data (image information) is transmitted by wirelesscommunication, and is ensured with an encryption strength equal to thatfor the above-described TMDS. Alternatively, the first encryption unit506 may compress image information of input content according to theimage information and thereafter encrypt the compressed imageinformation with the first encryption scheme. For compression of imageinformation, for example, a DCT/Wavelet transform (time-frequencycomponent transform) can be used.

The second encryption unit 508 has a function of encrypting imageinformation of content received by the wire communication unit 520, witha second encryption scheme. The second encryption scheme performsencryption based on the HDCP standard, specifically, encryption using ashared key which is shared only between those devices that are directlyconnected to each other in the course of an authentication process.Also, the second encryption unit 508 may TMDS-convert the encryptedimage information of content. Furthermore, the second encryption unit508 may perform a process in synchronization with an authenticationprocess by the HDCP authentication processing unit 510. Specifically,after authentication by the HDCP authentication processing unit 510succeeds, encryption with the second encryption scheme is performed.

The HDCP authentication processing unit 510 performs the above-describeddevice authentication and revocation process based on the HDCP standard,etc. The HDCP authentication processing unit 510 has a function ofobtaining device information of a device connected to the sink device500. The device information is, as described above, a KSV which isuniquely set according to a secret key of each device. KSVs areinformation obtained from a sink device to which image information is tobe transmitted, etc.

The control unit 504 has a function of performing control as to whetherto transmit and receive data using the wireless communication unit 518or transmit and receive data using the wire communication unit 520, bycontrolling switching of the switching unit 502 or the switching unit522. Specifically, when wireless communication is performed with thedata transmitting apparatus 100 by switching the switching unit 522,device information to be obtained by the device information obtainingunit 512 is obtained through the wireless communication unit 518. Whenwire communication is performed with the data transmitting apparatus100, the switching unit 522 is switched to obtain the device informationthrough the wire communication unit 520.

Next, data transmitting and receiving methods for the data transmittingand receiving system 2 will be described with reference to FIGS. 5 to 8.FIG. 5 is a flowchart showing data transmitting and receiving methodsfor the data transmitting and receiving system 2. As shown in FIG. 5, inthe data transmitting and receiving methods for the data transmittingand receiving system 2, a connection process by wireless communication(S100) is performed and thereafter an HDCP authentication process (S200)is performed. After the HDCP authentication process (S200) is performed,an image information transmission process (S300) is performed. Next,each of the connection process by wireless communication (S100), theHDCP authentication process (S200), and the image informationtransmission process (S300) will be described in detail.

First, a connection process by wireless communication performed in thedata transmitting and receiving system 2 will be described withreference to FIG. 6. FIG. 6 is a timing chart showing a connectionprocess by wireless communication performed in the data transmitting andreceiving system 2. As shown in FIG. 6, a connection process by wirelesscommunication is performed between the data transmitting apparatus 100and the sink device 500 including a data receiving apparatus. First, thesink device 500 including a data receiving apparatus notifies the datatransmitting apparatus 100 of start of a connection by wirelesscommunication (S102). The data transmitting apparatus 100 having beennotified by the sink device 500 of the start of a connection at stepS102 responds (ACK) to the start of a connection (S104).

The sink device 500 including a data receiving apparatus that hasreceived a response to the start of a connection from the datatransmitting apparatus 100 at step S104 transmits authenticationinformation of the sink device 500 including a data receiving apparatus(S106). The data transmitting apparatus 100 to which the authenticationinformation has been transmitted from the sink device 500 including adata receiving apparatus at step S106 transmits authenticationinformation of the data transmitting apparatus 100 (S108). Theauthentication information of the devices transmitted and received atsteps S106 and S108 are, for example, identification information of thedevices or information calculated based on the identificationinformation of the devices.

Then, based on the authentication information of the devices at stepsS106 and S108, authentication between the data transmitting apparatus100 and the sink device 500 including a data receiving apparatus isperformed (S110). This is all about a connection process by wirelesscommunication performed in the data transmitting and receiving system 2.When the authentication between the data transmitting apparatus 100 andthe sink device 500 including a data receiving apparatus succeeds atstep S110, an HDCP authentication process (S200) is performed. This isall about a connection process by wireless communication performed inthe data transmitting and receiving system 2.

Next, an HDCP authentication process performed in the data transmittingand receiving system 2 will be described with reference to FIG. 7. FIG.7 is a timing chart showing an HDCP authentication process performed inthe data transmitting and receiving system 2. As shown in FIG. 7, thesource device 400 notifies the receiving side of the data transmittingapparatus 100 of start of HDCP authentication (S202). Before the startof authentication is notified at step S202, a Hot Plug Detect request issent to the source device 400 from the sink device 500 through the datatransmitting apparatus 100. The source device 400 having notified of thestart of HDCP authentication at step S202 obtains authenticationinformation and a KSV (S204).

Then, the receiving side of the data transmitting apparatus 100 requeststhe transmitting side of the data transmitting apparatus 100 for HDCPauthentication of a subsequent stage (S206). The transmitting side ofthe data transmitting apparatus 100 having been requested by thereceiving side of the data transmitting apparatus 100 for theauthentication at step S206 notifies the sink device 500 of start ofHDCP authentication (S210). The transmitting side of the datatransmitting apparatus 100 having notified the sink device 500 of thestart of authentication at step S210 obtains authentication informationand a KSV of the sink device 500 (S212).

Then, the transmitting side of the data transmitting apparatus 100 sendsthe KSV to the receiving side of the data transmitting apparatus 100(S214). The source device 400 then obtains a KSV list from the receivingside of the data transmitting apparatus 100 (S216). The KSV list is, asdescribed above, a KSV list of unauthorized devices. The source device400 then checks the KSV list (S218).

This is all about an HDCP authentication process performed in the datatransmitting and receiving system 2. When at step S218 the source device400 determines that a destination to which image information of contentis to be transmitted is an authorized device, an image informationtransmission process (S300) is performed.

Next, an image information transmission process performed in the datatransmitting and receiving system 2 will be described with reference toFIG. 8. FIG. 8 is a timing chart showing an image informationtransmission process performed in the data transmitting and receivingsystem 2. As shown in FIG. 8, the source device 400 transmits encryptedimage information to the receiving side of the data transmittingapparatus 100 which is determined to be an authorized device at stepS218 (S302). The receiving side of the data transmitting apparatus 100to which the image information has been transmitted from the sourcedevice 400 at step S302 performs an image information transform, such asa DCT/Wavelet transform, on the image information (S304). The receivingside of the data transmitting apparatus 100 then encrypts the imageinformation transformed at step S304, to transmit the image informationby wireless communication (S306). The receiving side of the datatransmitting apparatus 100 sends the image information encrypted at stepS306 to the transmitting side of the data transmitting apparatus 100(S308).

The transmitting side of the data transmitting apparatus 100 to whichthe image information has been transmitted from the receiving side ofthe data transmitting apparatus 100 by wireless communication at stepS308 performs an image information transform such as DCT/Wavelettransform (S310). The transmitting side of the data transmittingapparatus 100 then encrypts the image information transformed at stepS310, to transmit the image information by wireless communication(S312). The transmitting side of the data transmitting apparatus 100transmits the image information encrypted at step S312 to the sinkdevice 500 (S314). When the data transmitting apparatus 100 is connectedto the sink device 500 by wire, the image information transmitted atstep S308 is encrypted based on the HDCP standard and thereafter theencrypted image information is TMDS-converted. Thereafter, theTMDS-converted image information is transmitted to the sink device 500via a TMDS signal path. This is all about an image informationtransmission process performed in the data transmitting and receivingsystem 2.

This is all about the data transmitting and receiving system 2 accordingto the first embodiment. According to the data transmitting andreceiving system 2, when the data transmitting apparatus 100 and thesink device 500 are connected to each other by wireless communication,image information of content output from the source device 400 isencrypted for transmission by wireless communication, with the validityof the sink device 500 being confirmed by an HDCP revocation process.Then, the encrypted image information is transmitted to the sink device500 which is wirelessly connected to the data transmitting apparatus100.

In the present embodiment, since the data transmitting apparatus 100 isprovided with a wire output, an HDCP revocation process can also beperformed on the data receiving apparatus 500 which is connected to thedata transmitting apparatus 100 by wireless communication. Likewise,since the sink device 500 is provided with a wire input, an HDCPrevocation process can also be performed on the sink device 500.Consequently, even in wireless communication, mutual authenticationbetween devices can be performed and a transmitting device and areceiving device can be arbitrarily combined. That is, even when HDCPsecurity information is not stored in a receiving apparatus or a sinkdevice, transmission and reception of content data can be performed withany device other than a specific transmitting apparatus, with thecopyright of the content data being protected.

Second Embodiment

A second embodiment describes the data transmitting and receiving system1 shown in FIG. 1 a. In the data transmitting and receiving system 1,the data transmitting apparatus 100 and the data receiving apparatus 200can be connected to each other by wireless communication or wirecommunication. The data transmitting apparatus 100 is connected by wireto the source device 400 and image information of content is input tothe data transmitting apparatus 100. The data receiving apparatus 200 isconnected to the sink device 300 wirelessly or by wire and imageinformation of content is input to the sink device 300 from the datareceiving apparatus 200.

In the present embodiment, also, since the source device 400 makes arevocation determination, KSVs of the data receiving apparatus 200connected to the data transmitting apparatus 100 and the sink device 300are transmitted to the source device 400 through the data transmittingapparatus 100.

As shown in FIG. 9, the data transmitting apparatus 100 includes aswitching unit 102, a control unit 104, a first encryption unit 106, asecond encryption unit 108, an HDCP authentication processing unit 110,a wireless communication unit 118, a wire communication unit 120, and aswitching unit 122. The data receiving apparatus 200 includes aswitching unit 202, a control unit 204, a first encryption unit 206, asecond encryption unit 208, an HDCP authentication processing unit 210,a device information obtaining unit 212, a verification unit 214, awireless communication unit 218, a wire communication unit 220, and aswitching unit 222.

The first encryption unit 106 has a function of encrypting imageinformation of input content with a first encryption scheme. The firstencryption scheme is used when content data (image information) istransmitted by wireless communication, and is ensured with an encryptionstrength equal to that for the above-described TMDS. Alternatively, thefirst encryption unit 106 may compress image information of inputcontent according to the image information and thereafter encrypt thecompressed image information with the first encryption scheme. Forcompression of image information, for example, a DCT/Wavelet transform(time-frequency component transform) can be used.

The second encryption unit 108 has a function of encrypting imageinformation of input content with a second encryption scheme. The secondencryption scheme performs encryption based on the HDCP standard,specifically, encryption using a shared key which is shared only betweenthose devices that are directly connected to each other in the course ofan authentication process. Also, the second encryption unit 108 mayTMDS-convert the encrypted image information of content. Furthermore,the second encryption unit 108 may perform a process in synchronizationwith an authentication process by the HDCP authentication processingunit 110. Specifically, after authentication by the HDCP authenticationprocessing unit 110 succeeds, encryption with the second encryptionscheme is performed.

The wireless communication unit 118 is a communication interface such asa wireless LAN compatible communication apparatus or a wireless USBcompatible communication apparatus. The wireless communication unit 118has a function of transmitting, by wireless communication, imageinformation encrypted by the first encryption unit 106.

The wire communication unit 120 is a communication interface such as awire communication apparatus which performs communication by wire. Anexample of the wire communication unit 120 includes a wire connectionunit that complies with the HDMI standard. The wire communication unit120 has a function of transmitting, by wire communication, imageinformation encrypted by the second encryption unit 108.

The HDCP authentication processing unit 110 has a function of obtainingdevice information of a device connected to the data transmittingapparatus 100. The device information is, as described above, a KSVwhich is uniquely set according to a secret key of each device. KSVs areinformation obtained from a sink device to which image information is tobe transmitted, etc.

The control unit 104 has a function of performing control as to whetherto transmit and receive data using the wireless communication unit 118or transmit and receive data using the wire communication unit 120, bycontrolling switching of the switching unit 102 or the switching unit122. Specifically, when wireless communication is performed with thedata receiving apparatus 200 by switching the switching unit 122, deviceinformation to be obtained by a device information obtaining unit 112 isobtained through the wireless communication unit 118. When wirecommunication is performed with the data receiving apparatus 200, theswitching unit 122 is switched to obtain the device information throughthe wire communication unit 120.

This is all about the functional configuration of the data transmittingapparatus 100. Next, the functional configuration of the data receivingapparatus 200 will be described. The wireless communication unit 218 isa communication interface such as a wireless LAN compatiblecommunication apparatus or a wireless USB compatible communicationapparatus. The wireless communication unit 218 has a function ofreceiving image information of content transmitted from the datatransmitting apparatus 100 by wireless communication.

The wire communication unit 220 is a communication interface such as awire communication apparatus which performs communication by wire. Anexample of the wire communication unit 220 includes a wire connectionunit that complies with the HDMI standard. The wire communication unit220 has a function of receiving image information of content transmittedfrom the data transmitting apparatus 100 by wire communication.

The first encryption unit 206 has a function of encrypting imageinformation of content received by the wireless communication unit 218,with a first encryption scheme. The first encryption scheme is used whencontent data (image information) is transmitted by wirelesscommunication, and is ensured with an encryption strength equal to thatfor the above-described TMDS. Alternatively, the first encryption unit206 may compress image information of input content according to theimage information and thereafter encrypt the compressed imageinformation with the first encryption scheme. For compression of imageinformation, for example, a DCT/Wavelet transform (time-frequencycomponent transform) can be used.

The second encryption unit 208 has a function of encrypting imageinformation of content received by the wire communication unit 220, witha second encryption scheme. The second encryption scheme performsencryption based on the HDCP standard, specifically, encryption using ashared key which is shared only between those devices that are directlyconnected to each other in the course of an authentication process.Also, the second encryption unit 208 may TMDS-convert the encryptedimage information of content. Furthermore, the second encryption unit208 may perform a process in synchronization with an authenticationprocess by the HDCP authentication processing unit 210. Specifically,after authentication by the HDCP authentication processing unit 210succeeds, encryption with the second encryption scheme is performed.

The HDCP authentication processing unit 210 performs the above-describeddevice authentication based on the HDCP standard. The HDCPauthentication processing unit 210 has a function of obtaining deviceinformation of a device connected to the data receiving apparatus 200.The device information is, as described above, a KSV which is uniquelyset according to a secret key of each device. KSVs are informationobtained from a sink device to which image information is to betransmitted, etc.

The control unit 204 has a function of performing control as to whetherto transmit and receive data using the wireless communication unit 218or transmit and receive data using the wire communication unit 220, bycontrolling switching of the switching unit 202 or the switching unit222. Specifically, when wireless communication is performed with thedata transmitting apparatus 100 by switching the switching unit 222,device information to be obtained by the device information obtainingunit 212 is obtained through the wireless communication unit 218. Whenwire communication is performed with the data transmitting apparatus100, the switching unit 222 is switched to obtain the device informationthrough the wire communication unit 220. This is all about thefunctional configuration of the data receiving apparatus 200.

A connection process by wireless communication, an HDCP authenticationprocess, and an image information transmission process according to thesecond embodiment are substantially the same as a connection process bywireless communication (S100), an HDCP authentication process (S200),and an image information transmission process (S300) according to thefirst embodiment and thus a detailed description thereof is omitted.

In the second embodiment, authentication by wireless communication isperformed between the transmitting side of the data transmittingapparatus 100 and the receiving side of the data receiving apparatus200. Then, a request for HDCP authentication of a subsequent stage isprovided to the sink device 300 from the data transmitting apparatus 100through the data receiving apparatus 200. Thereafter, authenticationinformation and a KSV of the sink device 300 are sent to the datatransmitting apparatus 100 through the data receiving apparatus 200. Thetransmitting side of the data transmitting apparatus 100 obtains a KSVlist and transmits the KSV list to the source device 400. The sourcedevice 400 then checks the KSV list.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

Although, in the above-described embodiments, a switching unit isprovided to switch between encryption with the first encryption schemeand encryption with the second encryption scheme, the present inventionis not limited thereto. For example, encryption may be performed withboth the first encryption scheme and the second encryption scheme andthe output of encrypted image information of content may be controlled.Alternatively, signal output from a TMDS circuit and signal output froma wireless transmitter-receiver may be controlled.

1. A data transmitting apparatus comprising: a first encryption unitthat encrypts image information of input content with a first encryptionscheme; a wireless communication unit that transmits, by wirelesscommunication, the image information encrypted by the first encryptionunit; a second encryption unit that encrypts image information of inputcontent with a second encryption scheme; a wire communication unit thattransmits, by wire communication, the image information encrypted by thesecond encryption unit; a device information obtaining unit that obtainsdevice information of a device connected to the data transmittingapparatus; a verification unit that verifies validity of a datareceiving apparatus, based on the device information obtained by thedevice information obtaining unit; and a control unit that performscontrol as to whether to obtain the device information through thewireless communication unit or obtain the device information through thewire communication unit, and as to whether to transmit the imageinformation encrypted by the first encryption unit from the wirelesscommunication unit or transmit the image information encrypted by thesecond encryption unit from the wire communication unit when theverification unit verifies that the data receiving apparatus isauthorized, wherein when the device information is obtained throughwireless communication and when the device information is obtainedthrough wired communication, a revocation process is performed todetermine whether the device is an unauthorized device by checkingwhether a key selection vector is included in a key selection vectorlist of unauthorized devices, wherein the device information obtainingunit obtains information on unauthorized devices from an externalapparatus, and when the device information of the data receivingapparatus is not included in the information on unauthorized devicesobtained by the device information obtaining unit, the verification unitdetermines that the data receiving apparatus is an authorized device. 2.The data transmitting apparatus according to claim 1, wherein when thedata transmitting apparatus is connected to the data receiving apparatusby wireless communication, the control unit controls the verificationunit to verify the validity of the data receiving apparatus and controlsthe first encryption unit to encrypt the image information.
 3. The datatransmitting apparatus according to claim 1, wherein the firstencryption unit compresses the image information of input contentaccording to the image information and thereafter encrypts thecompressed image information with the first encryption scheme.
 4. Thedata transmitting apparatus according to claim 1, wherein the secondencryption unit encrypts the image information of input content with thesecond encryption scheme and thereafter TMDS-converts the encryptedimage information.
 5. The data transmitting apparatus according to claim1, wherein the wire communication unit transmits the image informationof content through a TMDS circuit.
 6. A data receiving apparatuscomprising: a wireless communication unit that receives imageinformation of content by wireless communication from a datatransmitting apparatus connected to the data receiving apparatus; afirst decryption unit that decrypts the received image information ofcontent with a first decryption scheme; a wire communication unit thatreceives image information of content from the data transmittingapparatus by wire communication; a second decryption unit that decryptsthe received image information of content with a second decryptionscheme; a device information obtaining unit that obtains deviceinformation of a device connected to the data receiving apparatus; averification unit that verifies validity of the device, based on thedevice information obtained by the device information obtaining unit;and a control unit that performs control as to whether to obtain thedevice information through the wireless communication unit or obtain thedevice information through the wire communication unit, and as towhether to receive the image information by the wireless communicationunit and decrypt the image information by the first decryption unit orreceive the image information by the wire communication unit and decryptthe image information by the second decryption unit when theverification unit verifies that the device is authorized, wherein whenthe device information is obtained through wireless communication andwhen the device information is obtained through wired communication, arevocation process is performed to determine whether the device is anunauthorized device by checking whether a key selection vector isincluded in a key selection vector list of unauthorized devices, whereinthe device information obtaining unit obtains information onunauthorized devices from an external apparatus, and when the deviceinformation of the device is not included in the information onunauthorized devices obtained by the device information obtaining unit,the verification unit determines that the device is an authorizeddevice.
 7. The data receiving apparatus according to claim 6, whereinwhen the data receiving apparatus is connected to the device by wirelesscommunication, the control unit controls the verification unit to verifythe validity of the device and controls the first decryption unit todecrypt the image information.
 8. The data receiving apparatus accordingto claim 6, wherein the first decryption unit compresses the imageinformation of content according to the image information and thereafterdecrypts the compressed image information with the first decryptionscheme.
 9. The data receiving apparatus according to claim 6, whereinthe second decryption unit decrypts the image information of contentwith the second decryption scheme and thereafter TMDS-converts thedecrypted image information.
 10. The data receiving apparatus accordingto claim 6, wherein the wire communication unit receives the imageinformation of content through a TMDS circuit.
 11. A data receivingapparatus comprising: a wireless communication unit that receives imageinformation of content by wireless communication from a datatransmitting apparatus connected to the data receiving apparatus; afirst decryption unit that decrypts the received image information ofcontent with a first decryption scheme; a wire communication unit thatreceives image information of content from the data transmittingapparatus by wire communication; a second decryption unit that decryptsthe received image information of content with a second decryptionscheme; a device information transmitting unit that transmits deviceinformation of the data receiving apparatus; a verification resultobtaining unit that obtains a verification result of validity of thedata receiving apparatus which is verified by the data transmittingapparatus, based on the device information transmitted from the deviceinformation transmitting unit; a control unit that performs control asto whether to transmit the device information through the wirelesscommunication unit or transmit the device information through the wirecommunication unit, and as to whether to receive the image informationby the wireless communication unit and decrypt the image information bythe first decryption unit or receive the image information by the wirecommunication unit and decrypt the image information by the seconddecryption unit when the verification result obtaining unit obtains averification result that the data receiving apparatus is authorized; anda display screen generating unit that generates a display screencontaining the image information decrypted by the first decryption unitor the second decryption unit, wherein when the device information istransmitted through wireless communication and when the deviceinformation is transmitted through wired communication, a revocationprocess is performed to determine whether the device is an unauthorizeddevice by checking whether a key selection vector is included in a keyselection vector list of unauthorized devices, wherein the verificationresult obtaining unit obtains a verification result indicating that thedata receiving apparatus is an authorized device when the datatransmitting apparatus obtains information on unauthorized devices froman external apparatus and the device information of the data receivingapparatus is not included in the information on unauthorized devicesobtained by the data transmitting apparatus.
 12. The data receivingapparatus according to claim 11, wherein the display screen generatingunit is included in a display apparatus which is built in the datareceiving apparatus, the device information transmitting unit transmitsdevice information of the display apparatus, and the verification resultobtaining unit obtains a verification result of validity of the datareceiving apparatus which is verified by the data transmittingapparatus, based on the device information of the display apparatus. 13.The data receiving apparatus according to claim 11, wherein the firstdecryption scheme is used when image information of content istransmitted by wireless communication.
 14. The data receiving apparatusaccording to claim 11, wherein the second decryption scheme performsHDCP standard-based decryption on image information of contenttransmitted by wire communication.
 15. The data receiving apparatusaccording to claim 11, wherein the wire communication unit receives theimage information of content through a TMDS circuit.
 16. A datatransmitting method comprising the steps of: encrypting imageinformation of input content with a first encryption scheme; encryptingimage information of input content with a second encryption scheme;determining whether to obtain device information of a device connectedthrough a wireless communication unit that receives image information ofcontent by wireless communication or obtain the device informationthrough a wire communication unit that receives image information ofcontent by wire communication, and obtaining the device information ofthe device; verifying validity of a data receiving apparatus, based onthe obtained device information; and when the data receiving apparatusis verified to be authorized, performing control as to whether totransmit the image information encrypted with the first encryptionscheme from the wireless communication unit or transmit the imageinformation encrypted with the second encryption scheme from the wirecommunication unit, wherein when the device information is obtainedthrough wireless communication and when the device information isobtained through wired communication, a revocation process is performedto determine whether the device is an unauthorized device by checkingwhether a key selection vector is included in a key selection vectorlist of unauthorized devices, wherein information on unauthorizeddevices is obtained from an external apparatus, and when the deviceinformation of the data receiving apparatus is not included in theinformation on unauthorized devices, it is determined that the datareceiving apparatus is an authorized device.
 17. A data receiving methodcomprising the steps of: decrypting image information of contentreceived from a data transmitting apparatus, with a first decryptionscheme; decrypting image information of content received from the datatransmitting apparatus, with a second decryption scheme; performingcontrol as to whether to obtain device information of a device connectedthrough a wireless communication unit that receives image information ofcontent by wireless communication or obtain the device informationthrough a wire communication unit that receives image information ofcontent by wire communication; obtaining the device information of thedevice; verifying validity of the device, based on the obtained deviceinformation; and when the device is verified to be authorized,performing control as to whether to receive the image information by thewireless communication unit and decrypt the image information with thefirst decryption scheme or receive the image information by the wirecommunication unit and decrypt the image information with the seconddecryption scheme, wherein when the device information is obtainedthrough wireless communication and when the device information isobtained through wired communication, a revocation process is performedto determine whether the device is an unauthorized device by checkingwhether a key selection vector is included in a key selection vectorlist of unauthorized devices, wherein it is determined that the datareceiving apparatus is an authorized device when the data transmittingapparatus obtains information on unauthorized devices from an externalapparatus and the device information of the data receiving apparatus isnot included in the information on unauthorized devices obtained by thedata transmitting apparatus.
 18. A data receiving method comprising thesteps of: decrypting image information of content received from a datatransmitting apparatus, with a first decryption scheme; decrypting imageinformation of content received from the data transmitting apparatus,with a second decryption scheme; performing control as to whether totransmit device information of a data receiving apparatus through awireless communication unit that receives image information of contentby wireless communication or transmit the device information through awire communication unit that receives image information of content bywire communication; transmitting the device information; obtaining averification result of validity of the data receiving apparatus which isverified by the data transmitting apparatus, based on the transmitteddevice information; when a verification result that the data receivingapparatus is authorized is obtained, performing control as to whether toreceive the image information by the wireless communication unit anddecrypt the image information with the first decryption scheme orreceive the image information by the wire communication unit and decryptthe image information with the second decryption scheme; and generatinga display screen containing the image information decrypted with thefirst decryption scheme or the second decryption scheme, wherein whenthe device information is transmitted through wireless communication andwhen the device information is transmitted through wired communication,a revocation process is performed to determine whether the device is anunauthorized device by checking whether a key selection vector isincluded in a key selection vector list of unauthorized devices, whereinit is determined that the data receiving apparatus is an authorizeddevice when the data transmitting apparatus obtains information onunauthorized devices from an external apparatus and the deviceinformation of the data receiving apparatus is not included in theinformation on unauthorized devices obtained by the data transmittingapparatus.